Apparatus for causing intermittent operation of a hydraulic motor



Aug. 26, 1958 F. B. L EvETUs ETAL 2,843,873

APPARATUS FOR cAusING INTERMITTENT OPERATION oF A HYDRAULIC MOTOR FileaNov. 25, 1955 Accumu/arar Hydrau/ic Mafar BY .f1/Azam 64m@ vgl/gm ATTQQNEY United States Patent() Francis Benjamin Levetus and Alan Roy .Hysloll Cventry, England, Afassignors to Ille Keelavite Company Limited, Coventry, England, a British company Application November 125, '17955, Serial No. 549,133

'Claims priority, am,licaliv Greattrifatl -llovember 26, .1954

This Tinven'tin Irela'tes `'to apparatus for causing linter- Vmitteilt 'operation of ahydrauliemotor, which term is Vto be understood 'as l"in'cluc'iing rotary Ahydraulic motors fof "the rotary piston, reciprocating piston 'or 'other type 4as well as motors of the ram, or like type, and has for its object 'to 'provide a form 'of lapparatus by which a hydraulic motor 'may vbe caused Cto operate 'in a series of steps, which can be exactly determined and consistent and may take place in 'rapid 'succession :and yet ihave to vbe 4separated by a relatively long period of rest so .that rapid accurate operation is necessary, as vfor vex'ani'ple when the hydraulic motor is `used to effect the 4'feed in a tube reducing machine of the kind `in which-reducing-rollers are Vmoved rapidly back and forth overt-tithe tube gan'd have gaps therein which ,relieve thepressure on die tube'momentarilyat one end of each stroke ofthe rollers toipermit the tube to be advanced by feed mechanism.

Apparatus for causing intermittent operation of a hydraulic motor in predetermined steps according to the present invention comprises a hydraulic system (hereinafter for convenience called the accumulator system), and including an accumulator device having a movable piston or the equivalent (hereinafter called the accumulator piston) which has one position (hereinafter called for convenience the discharged position) in which the uid capacity of the accumulator system is at its minimum and a second position (hereinafter for convenience called the charged position), determined by a stop which limits its movement, so that there is a predetermined difference in the volume of the accumulator system respectively when the accumulator piston occupies its charged and discharged position, means by which fluid is delivered to the accumulator system to cause movement of the accumulator piston from its discharged position to its charged position, and this supply is then cut off, means by which, after the accumulator piston has reached its charged position, the hydraulic motor can be started, a metering pump arranged to be driven from the hydraulic motor and through which discharge of uid from the accumulator system then takes place so as to cause the return of the accumulator piston to its discharged position and means :by which when the accumulator piston reaches its discharged position, the hydraulic motor is stopped.

One form of the apparatus according to the invention is shown diagrammatically in the accompanying drawings in which:

Figure 1 shows the apparatus with the various parts thereof in the positions which they occupy in readiness for the time when the hydraulic motor is to perform one step;

Figure 2 shows the apparatus with the various parts in the positions which they occupy during the performance of such a step; and

Figure 3 is a sectional view illustrating a conventional relief valve employed in the apparatus of Figures 1 and 2.

In the drawings 1 is the hydraulic motor which is to be intermittently operated. The hydraulic motor l is ar- ,.-ranged -to be fed with operating uid through an inlet passage -2 from a source of supply comprising a pump 3 `arranged to deliver operating fluid under :pressure to an inlet passage 4 communicating with an accumulator 5 Y'and :containing a pressure relief valve 6 by which surplus :duid can escape to a relief passage 7 and a non return -va-lve `8.

The admission of working fluid from the :passage 4 to Athepassage 2 to cause operation of the hydraulic motor 1 is controlled by a valve 9 of the piston type arranged Within 1a casing 10 and -acted upon yat one end bya spring 4121 "and at its other end by the pressure in a passage 12. The relief passage 7 also communicates with the casing vL10 'and the construction of the valve is such that it can either occupy an inoperative position as shown in lFigure 1 :in which the passage 2 communicates Vwith the relief passage 7 oran operative position as shown in Figure 2 in which the inlet passage 4 communicates with the pasfsage 2,.

The hydraulic motor 1 is arranged to drive a metering pump 13 through a chain 14,*the metering pump 13 being arranged to accept fluid from the passage `1-2 and deliver it to a discharge passage 15.

vAssociated with the inlet passage 2, 4the outlet passage '16 of the hydraulic motor 1 and the discharge passage 15 :is 'a valve device 1'7 of known type, shown more particui casing 19 'of a piston type changeover valve having further ports 20, 21, 22 and 23 of which the ports 2li and 23 communicate with a passage 24, the port 21 communicates with a relief passage 25 while the port 22 communicates with a passage 26 connected to a source of hydraulic pressure.

The passages 24 and 26 4communicate with opposite ends of a cylinder 27 constituting the cylinder of an accumulator device, containing a piston 28 having a piston rod 29 passing in a uid tight manner through one end of the cylinder and having its travel to the right in the drawings limited by an adjustable stop 30. The movable piston member 31 of the valve 19 has four lands 32, 33, 34,

35 as shown, and is acted upon at one end by a compression spring 36 and at its other end by a cam 37 including at least one cylindrical surface 38 of constant radius and at least one lobe 39.

The operation of the apparatus is as follows:

When the valve member 31 bears against the cylindrical part 38 of the cam 37 as shown in Figure 1 it will be seen that the passage 26 which communicates at all times with the right hand end of the cylinder 27, is brought into communication by way of the ports 22 and 23 and the passage 24 also with the left hand end of the cylinder 27 with the result that the pressure from the passage 26 acting differentially on the two faces of the piston 28 move it to the right until its piston rod 29 engages the adjustable stop 30 as shown. At this time it Will be apparent that the ports 20 and 18 communicate with closed chambers Within the valve 19 while the passage 25 is closed by the land 34. At this time also for reasons hereinafter explained, the valve 9 Will occupy the position shown in which the passage 2 communicates with the passage 7 and the motor 1 is therefore stationary.

When the rotation of the cam 37 brings the lobe 39 around into position so as to move the valve member 31 into the position shown in Figure 2, it will be seen that the passage 24 is now connected through the ports 20 and 18 and the passage 12 to the lower end of the casing 10 of the valve 9, the port 23 communicates with the closed chamber, the port 22 is closediby the land 34 andV` i the port 21'communicates with the closed'chamber. The

pressure acting through the passage 26 now therefore Vmoves the piston 28 to the left so that the pressure thus created in the passages 24 and 12 moves the valve Y9 into 5 the position shown in Figure 2 in which the passage4; is

-brought into-communicationrwith the `passage 2. The hydraulic motor -1 is therefore caused to` rotate and to,

cause simultaneous rotation of the metering pump'` .13 Vwhich therefore begins to accept uid from the passage 10:

12 and discharge it into the passage 15. rlhe pistonA 428 therefore moves to the left under the pressure acting on its righthand face to maintain the pressure in the passages n 24 and 12 substantially unchanged until the piston 28 Vreaches the left 'hand end of the cylinder 27 audits 'fur- 15 thertmovement is therefore prevented. When this occurs the"- continued rotation of the hydraulic motor 1 and metering pump 13 by accepting further fluid from the passage 12 allows the valve 9 to move downwards under the inuence Vof its spring into the position shownvin 20` Figure l'and thus stop further rotation of the hydraulic motor-1.'

`When the cam 37 continues its rotation to bring the part V158 thereof again Yinto engagement with the end'of the valve `member 31 `so that this valve member again oc- 25 cupies the position shown in Figure l, the piston 28 will again be forced to the right as shownin Figure l, and the cycle of operation repeated.

It will be apparent that the degree of rotationof the hydraulic motor 1 following each step Will be determined 30 by the volume of kfluid in the left hand end of the cylinder 27 when this rotation begins and hence by the setting of theadjustable stop 30. The metering pump 13.V may be of xed capacity or variable capacity type and 1n the latter case it will be apparent that the degree of rotation 35 of the hydraulic motorl during each step it is in operation can be. adjustedby adjustment of the capacity of` the meteringw pump as well as by yadjustment of the stop 30.

It'will be apparent that although in the example shown the valve 31 is arranged to be operated by a rotating cam 37, the movemento'f- `'this valve from one of its positions :tothe other Will'be effected byany convenient means infres'ponse to any convenient signal.`

What we claim as our invention and desire to secure by' Letters lPatent isz-v 1 li-Apparatus lfor causingv intermittenty operation of a .sive means, operatively connected to the controlfirvalve and responsive tothe pressurein the accumulator system to start themotorwhen-the accumulator deviceis charged vand to. stop thel motor when the accumulator has been discharged. v Y t v 2..Appa ratus as claimedinclaim lincludingmeans for varying thecapacityvofgthe accumulator device.

Y, .3. /Apparatus asV claimed-in claim 1 in which-the'meteringpump is of the variable capacity type.

i vReferences Cited inthe Ifile of thispatent UNITED ,STATES PATENTS 

